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Summary: Encodes the chloroplast PPR4 protein required for trans-splicing the rps12-1 group II intron. The null allele of ppr4 (ppr4-1) is albino; and a weak allele (ppr4-2) is pale green. Both condition a non-photosynthetic, seedling lethal phenotype due to the failure to splice the rps12 mRNA. This splicing defect blocks the biogenesis of the plastid translation machinery, which in turn leads to the loss of all plastid-encoded proteins.
Images: mutant leaf colors depicted on a seedling leaf color scale
First reported: Schmitz-Linneweber et al. 2006.
Key Alleles
ppr4-1::Mu9; Mu9 insertion in the first exon. Ivory, seedling lethal phenotype. Mutants are smaller than wild type siblings.
ppr4-2::Mu1; Mu1 insertion in the first intron. Pale green, seedling lethal phenotype. Heteroallelic progeny of complementation crosses between ppr4-1::Mu1 and ppr4-2::Mu9 have an intermediate phenotype.
Gene Product
PPR4, localized to chloroplast stroma, specifically associates with the first intron of rps12 pre-mRNA. This intron is transcribed in segments.
Related loci
rps12; PPR4 is required for the rps12 trans-splicing reaction (Schmitz-Linneweber et al. 2006).
Not allelic to hcf7.
References
Schmitz-Linneweber C, Williams-Carrier RE, Williams-Voelker PM, Kroeger TS, Vichas A, Barkan A (2006) A Pentatricopeptide Repeat Protein Facilitates the trans-Splicing of the Maize Chloroplast rps12 Pre-mRNA. Plant Cell 18: 2650-2663. PUBMED